Clean Power

Published on July 17th, 2014 | by James Ayre


New Solar CPV Module Efficiency World Record Set — 36.7% Efficiency Achieved Thanks To Fraunhofer ISE And Soitec Collaboration

July 17th, 2014 by  

A new conversion efficiency world record for concentrator photovoltaic modules (CPV), of 36.7%, was recently set thanks to a research collaboration between the Fraunhofer Institute for Solar Energy Systems ISE and the French CPV developer Soitec (along with the French research center CEA-Leti, and the Helmholtz Center in Berlin).

The researchers from Fraunhofer ISE — based in Freiburg, Germany — have spent the last few years working on the CPV module technology known as FLATCON, utilizing fresnel lenses to bundle and focus sunlight onto miniature, super efficient solar cells. The new record was achieved by combining this work with the adaption of a new wafer bonding solar cell structure developed together with Soitec.

Newest FLATCON concentrator module with an efficiency of 36.7%.  Image Credit: ©Fraunhofer ISE

By incorporating the said four-junction (GaInP, GaAs, GaInAs and InP) solar cell structure into the Fraunhofer ISE module concept, sunlight can be concentrated “by a factor of 230 suns onto fifty-two 7 mm2 miniature solar cells, with the help of fifty-two 16 cm2 Fresnel lenses.”

“Naturally we are incredibly excited about this high module efficiency,” stated Dr Andreas Bett, who leads the CPV research at Fraunhofer ISE.

The new work, according to Dr Bett, proves that the high efficiencies of Soitec’s novel four-junction solar cells can be carried over to the module level.

RenewEconomy provides a bit more information:

Concentrator photovoltaic systems (CPV) are installed in sun-rich regions, where such systems produce solar electricity for less than 8 eurocents per kilowatt-hour.

The key to the technology is the solar cell efficiency and the concentrating optic. In the record module, the newly developed four-junction solar cell was combined with Fresnel lenses, which were manufactured by the industry partner ORAFOL Fresnel Optics based on a new Fraunhofer design.

This new work is expected (by the researchers) to be incorporated into commercially manufactured modules within the next one to two years.

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's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.

  • Wayne Williamson

    Cool, my question is how much does it cost for say a normal 2 sq meter panel.

  • Standard PV panels on single axis trackers make good financial sense at the utility scale and should the tracker fail you will still get the majority of the production on that array segment. CPV with dual axis tracking is many times more complex and you lose much of the elegance that comes from the simplicity of standard PV arrays.

    • Bob_Wallace

      That math may not hold as panel prices continue to fall. We’re now at $2/watt. But when installed hits $1/watt and continues lower….

      BTW, do you know the cost per watt to add tracking?

      • Ronald Brakels

        One figure I just read but don’t know how accurate it is, is that concentrating PV is close to $1 a watt while flat panel PV is less than half that amount.

        • Bob_Wallace

          That could easily be. But ConPV hasn’t had much opportunity to scale.
          Overall, I think wind and PV solar are going to get so cheap that there’s not going to be much room for any other generation, with the exception of dispatchable for deep backup. There will obviously be some exceptions such as Iceland which has enormous geothermal resources, but in general wind/solar.

          I suspect wave is going to drop away soon.

          • Ronald Brakels

            I can see concentrating solar power with tracking being put on a flat roof to get the maximum amount of energy from a limited area as possible, which could come in handy in crowded places like Taipei, but for most applications flat panel PV is going to win on cost. And even in Taipei once the cost gets low enough they can put PV on east and west facing walls. Even little things like being able to stack more flat panels in a cargo contaner matter. And while tracking is good for early morning and late afternoon power, it will still have to compete with placing flat panels on east and west facing roofs. (Or using PV roofing materials, which will probably catch on once the age of the retrofit is over.) But I am glad that people are working on this. It does have applications and may end up being more useful than I think.

          • Ronald Brakels

            Wave energy, well, I won’t count it out at the moment. Since water is much denser than air the dream is to capture energy from it at a lower capital cost than wind, but in practice that’s not working out at the moment, is it? But there is still potential there. Here in South Australia we have for all practical purposes infinite wind power, infinite solar power, and infinite wave power, so it would be nice if we could get that third one going just to round out the trifecta. (We also have an enormous amount of uranium, but that’s not practical.) In Northern Europe with its cold and dark winters wave power might have a useful niche. But in Australia with out summer peak demand, vast wind and solar resources, considerable hydro power for such a flat dry land, and home and business energy storage looking better all the time, it may never take off here despite our excellent wave resources.

            Oh, and in South Australia we also have infinite hot rock geothermal power for practical purposes, but that’s currently hanging out with wave power at the moment.

          • JamesWimberley

            The difference is that wave is weather-dependent like wind and solar, while geo is 95%+ reliable and despatchable. I know where I would put my long-shot money.

          • Ronald Brakels

            Wave energy availability is pretty much constant here in our wavey areas. Of course, so are the winds at those locations. I’ve got to remember that in other places waves aren’t an all the time thing. And our Australian geothermal is with with our Australian wave energy. In the morgue. They both died of massive funding cuts. But other people in other lands are making a go of hot rock geothermal. I wish them success and salute them as Port Adelaide slowly sinks beneath the waves.

      • The leading utility scale technology at the moment is thin film with single axis tracking installed at about $1.70/watt. Single axis tracking increases energy output by about 30%. Therefore, adding tracking must be less than $0.40/watt, otherwise fixed tilt would be dominating.

  • JamesWimberley

    CPV is still not going anywhere. I understand the insoluble problem is the cost of the highly accurate trackers.

    • Bob_Wallace

      I wonder. If the lens and cell are rigidly connected then the device just has to be aimed. Take a look at the setup in the picture. Beef it up just a bit to keep the wind from flexing the front panel.

      Now create a “Where’s the Sun?” sensor which can be as simple as five photodetectors at the bottom of a well. One in the center, the others above/below/left/right. By comparing power coming from each it’s pretty simple to adjust for ‘dead on’.

      A Raspberry Pi could be the brains for probably hundreds of arrays. An adjustment every few seconds would be more than adequate. The rest is also just engineering.

      • Benjamin Nead

        Sure . . . but we’re talking about a PV “panel” that is now about a foot tall, with air space in between and, as a result, being far more susceptible to wind shear. In most places you’re also going to witness a tendency for pigeons and other small wildlife wanting to roost underneath the lenses (and, of course, roasting when the Sun comes out.)

        The electronics of a tracker might be cheaper today than when they were more commonly utilized. But it’s still going to be tied to mechanical elements that have to be robust and, hopefully, relatively maintenance-free. These are the same issues we’ve historically seen with all electro-mechanical trackers and why we’ve seen them replaced in more recent years by more efficient (conventional, flat) PV panels and better (MPPT, etc.) charge controllers.

        • Bob_Wallace

          First paragraph – just engineering. Enclose the space between the lenses and cells with some sort of rigid screening.

          Mount the array within a ‘wind screen’ in high wind areas. Just a tall wind-defecting fence on the prevailing wind side(s).

          The control system for unit adjustment could be mechanical or hydraulic. With a mechanical system it could be “move and lock”. With a hydraulic system you need one sturdy hydraulic cylinder at each corner.

          Either a locked mechanical or hydraulic system is going to provide a lot of resistance to wind movement. Hydraulic fluid is hard to compress.

          Tracking is probably dead for PV. Panel prices have become so low. I don’t know if CPV is financially competitive, but tracking costs should not make or kill them.

          • Offgridman

            First off sorry for not having a link available for this, but in an article from the past few months discussing fresnel or another type of concentrator lens it was directly applied to the PV cell. This greatly reduced the need for any tracking and made a non issue of the space in between. Of course some tracking movement to extend the hours of collection for a longer time would have been helpful, but part of the advantage of this concentrator was that it did it on its own.
            Also as a side note saw plans for a solar oven many years ago that would follow the movement of the sun (single axis east/weat) done with just one light sensor from an on at night security light by extremely restricting the aperture. So maybe sun tracking solar panels won’t require as many sensors as you were thinking. The way they did it was the light sensor let power pass to the tracking motor until light was sensed through the smaller opening (daytime), then it shut it down. When the sun moved some the sensor thought it was dark outside again and gave power to the tracking motor again until lined up.

          • Bob_Wallace

            The sensors are so cheap (there’s one in a $3 nite light as you point out) that they could use a whole bunch and not drive the price of power closer than five digits right of the decimal point. And there are probably much slicker ways to do the job.

            It seems to me that a hydraulic tracking system is worth considering. With a piston at each corner and a sensing system that could optimize for tilt and angle there would be lots of control and a lot of resistance to wind movement. Off the shelf hardware.

          • Offgridman

            Yes we have the tech, even if they were done with the electric actuator arms like are used in dump bed conversions or automated hatchbacks in car conversions, to avoid the maintenance of hydraulics.
            Concentrator lenses and moving panels will become a much more important issue in the cities where the concern of limited space becomes an issue when we are finally getting the rest of society off from the reliance on fossil fuels for the generation of electricity.

          • Bob_Wallace

            Another approach. Perhaps better. Taking a look at what is available –

            ” With both standard and customizable stroke lengths up to 915 mm (36 in), these families can provide full load forces as high as 6670 N (1500 lbf). Available in both DC (12, 24, 36) and AC (115, 230, 400) voltage models, these actuators come optionally packaged with a wide selection of controls and accessories. For higher loads, longer strokes or other custom requirements, please contact the factory.”

            Why not?

          • Offgridman

            You get where I am coming from, less maintenance with no hydraulic systems to take care of, and these could be directly powered by the panels they are moving.. And with the minimal drain of the dead eye light sensors no power drain except when panels need to be moved, and a return to start point from the final rays of the setting sun.

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